案例要求：创建一个 Studentservice 类，其中需要使用 studentDao 接口的保存方法，来存储一个Student 类的对象，StudentDao 接口有两个不同的实现类，通过 Spring 的方式，为 Student类创建对象并为属性赋值，并通过 Spring 的方式，创建 Studentservice 类的对象以及StudentDao 接口的一个实现类对象，通过依赖注入的方式模拟完成保存的操作。

1、配置依赖

在pom.xml中配置依赖

<dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.2.0.RELEASE</version>
</dependency>

2、创建applicationContext.xml文件，并且点击File->Project...->找到Spring,点击+，选中文件导入

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"><bean id="student" class="cn.clz.pojo.Student"><property name="name" value="海绵宝宝"></property><property name="age" value="18"></property></bean><bean id="studentDao1" class="cn.clz.dao.impl.StudentDaoImpl1"></bean><bean id="studentDao2" class="cn.clz.dao.impl.StudentDaoImpl2"></bean><bean id="studentService" class="cn.clz.service.StudentService"><property name="studentDao" ref="studentDao1"></property></bean>
</beans>

3、创建实体类Student、接口StudentDao、接口实现类StudentDaoImpl1和实现类StudentDaoImpl2、类StudentService

Student.java

public class Student {private  String name;private  int age;public Student() {}public Student(String name, int age) {this.name = name;this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {return "Student{" +"name='" + name + '\'' +", age=" + age +'}';}
}

StudentDao.java

public interface StudentDao {void save();
}

StudentDaoImpl1.java

public class StudentDaoImpl1 implements StudentDao {public void save() {System.out.println("实现类1实现StudentDao的save方法...");}
}

StudentDaoImpl1.java

public class StudentDaoImpl2 implements StudentDao {public void save() {System.out.println("实现类2实现StudentDao的save方法...");}
}

StudentService.java

public class StudentService {private  StudentDao studentDao;public void save(){studentDao.save();}public StudentDao getStudentDao() {return studentDao;}public void setStudentDao(StudentDao studentDao) {this.studentDao = studentDao;}}

4、编写测试TestStudent.java

public class TestStudent {public static void main(String[] args) {//加载spring容器ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");Student student = (Student) ctx.getBean("student");StudentService studentService = (StudentService) ctx.getBean("studentService");System.out.println(student);studentService.save();}
}

5、运行结果